CN101170279A

CN101170279A - Dual-bridge DC-DC converter and its control method

Info

Publication number: CN101170279A
Application number: CNA2007101942698A
Authority: CN
Inventors: 叶忠
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-12-11
Filing date: 2007-12-11
Publication date: 2008-04-30
Anticipated expiration: 2027-12-11
Also published as: CN101170279B

Abstract

The invention discloses a DC-DC converter circuit and a relevant control method; wherein, the converter comprises two DC-AC inverters; each can create symmetrical and isolated square waves or other similar AC output voltage. Through the movement of the phase of one of the DC-AC inverters, the overlapping part of the corresponding voltage of a DC output filtration circuit, which is the two DC-AC inverters can be applied to, will be changed accordingly, so as to reach the target of regulating the output voltage. A double half-bridge and double full-bridge DC-DC converters are two typical types of the converters. During normal running process, the bridge-type inverter is always running in a 50 percent of duty cycle, so as to fulfill Zero Voltage Switching (ZVS) in broad loads. Meanwhile, the invention can also eliminate circulation current, so as to improve the efficiency of power conversion. As for the adjustment and startup of low output voltage, the circuit can work in a Pulse Width Modulation (PWM) status.

Description

Dual-bridge DC-DC converter and control method thereof

Technical field

The DC-DC converter that the present invention relates to (DC-DC Converter), this converter has two power transformers, and mixes control with PWM and phase shift, and has the feature of wide year ZVS and zero circulating current.The more particularly two half-bridges and the bridge DC-DC converter of enjoying a double blessing.

Background technology

In field of power conversion, normally use the HF switch technology, direct current is transformed to the electric pressure of another isolation from an electric pressure.The use of switching technique has greatly reduced the volume of converter, and has improved conversion efficiency.When industrial quarters was enjoyed this switching technique, it faced new challenges again, and these challenges comprise further raising conversion efficiency, reduced volume and reduced the electromagnetic interference (EMI) that is caused by switching voltage and electric current.For these challenges, people concentrate on following 4 aspects to many effort:

1, wide year zero voltage switch is switched (ZVS);

2, eliminate circulating current;

3, export the recovery that rectifying tube oppositely recovers energy;

4, the clamper and the elimination of the reverse oscillating voltage of output rectifying tube;

And develop many good technical.These technology comprise the full-bridge converter of phase-shifting full-bridge formula or PWM control and asymmetrical half-bridge converter etc.The most extensively usefulness is phase-shifted full-bridge converter, especially on high-power field.Texas Instruments company has gone up at its application note U-136A " Phase-Shifted Zero Voltage Transition Design Considerationand the UC3875 PWM Controller " this circuit has been done detailed introduction.The phase-shifting full-bridge DC-DC converter of indication is to rely on to comprise that electric current that transformer magnetizing current and secondary are coupled to former limit charges and discharge the parasitic capacitance of lagging leg switching tube.Simultaneously it also relies on circulating current and the energy that is stored on the transformer leakage inductance excites transformer leakage inductance and the vibration between the arm parasitic capacitance in advance.When output current reached certain value, the parasitic capacitance of switch original paper can be full of electricity fully or have been put in the grid Dead Time.The switching tube conducting that then can when its output end voltage reduces to zero, be triggered.This switching technique is so-called zero voltage switch and switches (ZVS) and since the parasitic capacitance of switching tube when no-voltage noenergy switching tube is discharged.Switching loss has promptly been eliminated in being controlled at like this in certain loading range.Yet at remaining light loading district, the switching tube conducting that have to when its parasitic capacitance also has voltage, just be triggered.At this moment, the energy on the parasitic capacitance promptly all is discharged in the switching tube.This non-zero voltage switch causes the switching loss of part and more serious electromagnetic interference.In underloading, especially zero when carrying, and effectively duty ratio and the corresponding weber value that is added on the power transformer become at the outputting inductance electric current and to diminish when discontinuous.In this case, output current and transformer magnetizing current that secondary is coupled to former limit all can't fully reduce the voltage of switching tube output when switching tube is wanted conducting, and cause quite significant switching loss.The person, this topology almost can't reclaim by the output rectifier diode oppositely to be recovered and the leakage field energy that causes, the voltage oscillation on also uncontrollable former secondary two limits that caused by this leakage field energy.The final part of this energy consumes on loop of power circuit.Another part then is launched into the space with the form of electromagnetic energy, thus heating that causes and EMI problem.

For alleviating above problem, Richard Redl etc. has invented a simple and effective circuit.See United States Patent (USP) 5198969[2 for details].Power transformer and the node that links to each other of vibration inductance by pair of diodes its clamper to direct current import+utmost point and the-utmost point.This clamp circuit with vibration inductance has reduced to capture the energy of this transient current on former limit, and significantly reduce the voltage oscillation on former secondary two limits by exporting the transient current that rectifier cell causes.The energy that is captured to is stored in the vibration inductance with the form of electric current, and by this vibration inductance, circulates in the loop of a clamp diode and a switching tube composition.This energy part is depleted on the circuit with the form of heat, and another part energy then is used for vibration when this switch opens, and feeds back to the input power supply.Use the vibration inductance of big inductance value can reduce the current changing rate of output rectifier, thereby reduce this transient current.Be under the situation of cost with the loss duty ratio, to a certain extent, the efficient of circuit is improved.Use the vibration inductance of big inductance value also can increase the ZVS of underloading scope.

For further increasing the ZVS scope of underloading, many circuit are invented.These circuit can be classified as two classes: the first kind is the oscillation network by auxiliary switch control.This auxiliary switch is triggering and conducting when zero current normally, and excites the vibration of oscillation network to produce the condition of main switch ZVS.Another kind of then is the LC network that simply links to each other with main switch.This network can produce the oscillating current that has nothing to do with load makes the main switch on the brachium pontis be operated in the ZVS state at big loading range.

A circuit by Pradeep Madhay Bhagway invention then is one of them example.The U.S. Patent number that this circuit is relevant is 5875103 " Full Range Soft-Switching DC-DC Converter " [3].These circuit increase the loading range of ZVS really, but their not mentioned other above several problems.

The circulating current that depends on load is the major defect of existing ZVS full-bridge circuit.On two of full-bridge circuit switching tube or down during the switching tube conducting circulating current pass through, comprise two brachium pontis main switches, vibration inductance (if any), the former secondary coil of power transformer, rectifier is at interior most of loop of power circuit.Energy is not delivered to secondary from former limit during this, and this circulating current causes quite serious power loss.United States Patent (USP) (patent No. 5946200) " Circulating CurrentFree Type High Frequency Soft Switching Pulse-Width Modulated Full BridgeDC/DC Converter " [4] has been introduced one and has been utilized the oscillation network of secondary that the circulating energy on former limit is all moved on to dc output end, thereby thoroughly eliminated circulating current, with and relevant power consumption.Yet this oscillation network is but also extracted the energy of the necessity that is used for ZVC out, thereby makes leading arm switch pipe be almost triggering and conducting under the DC source voltage condition at its output end voltage.This total head triggering and conducting has caused some switching losses, and may cause the EMI problem.Owing to this reason, some have the switch element of big parasitic capacitance, as MOSFET (metal oxide silicium field effect transistor) etc., also just may not conform to and are suitable for this topology.Another shortcoming is exactly, and compares with the full-bridge converter with diode clamp (by Richard Redl invention), because the vibration of oscillation network, back-pressure voltage of its output rectifier cell of this circuit is much higher, especially when starting.

The another kind of method of eliminating circulating current is used asymmetric (duty ratio) control exactly, and asymmetrical half-bridge and asymmetric full-bridge converter can be arranged with the circuit of this control.United States Patent (USP) (patent No. 6496396) " Reverse Recovery Circuit, Method of Operation Thereof And Asymmetrical Half-Bridge PowerConverter " [5] right title half-bridge has been made detailed description.Under some conditions, it is fairly good that asymmetric bridge dc dc converter can be worked.These conditions comprise little input, output voltage range and little or slow load changing.If these conditions are not being met, circuit might enter serious asymmetrical state, thereby makes circuit lose soft switch (ZVS), and the electric current pressure of switching tube and the voltage pressure of output rectifier cell are increased.Because main circuit current must flow through half-bridge electric capacity, capacitance is corresponding to be selected greatlyyer, and the change in voltage on the electric capacity just may not catch up with the variation of the duty ratio of PWM yet when load variations.Thus, heavy load changes the magnetic bias that just causes main transformer easily and saturated.Therefore, asymmetrical half-bridge can't be used for high-power circuit; When design, its zero crossing frequency is also wanted the end relatively than conventional bridge circuit.

Although these trials are alleviating the electric stress of power consumption and element in varying degrees, they all can't overcome the problem aspect above-mentioned 4 simultaneously on a circuit.The industrial quarters such circuit that always waits in expectation, it can realize ZVS in the scope at wide year, duty ratio is always constant in maximum, make full use of magnetic element, farthest reduce or eliminate circulating current, regain and oppositely to recover energy, and clamper or eliminate the voltage oscillation of output rectifier cell well.The present invention begins to involve in " forbidden zone " in the control, and promptly converter can be operated in the maximum duty cycle state in fact, and it can adjust its output voltage again simultaneously.In this " forbidden zone " lining, excellent characteristic is able to realize in a circuit in many existing topologys, thereby circuit efficiency and whole runnability are reached a new high.

Summary of the invention

The present invention seeks to provide a kind of dual-bridge DC-DC converter and control method thereof, is intended to the maximum land productivity magnetic original paper of limiting the quantity of, and reduces semiconductor original paper stress and electromagnetic interference (EMI), and improves the efficient of power converter.

Dual-bridge DC-DC converter of the present invention, it is characterized in that: described dual-bridge DC-DC converter comprises inverter, rectifier and filter, direct voltage is input to inverter, the interchange output of inverter is input to the ac input end of rectifier again, and the dc output end of rectifier is again by the direct voltage behind the filter output transform;

Described inverter is made up of the first and second two DC-AC inverters, and each DC-AC inverter has two first and second ac output end mouths of isolating mutually again;

Described rectifier is made up of the first and second two full-wave rectifying circuits, and each full-wave rectifying circuit is made up of rectifier and continued flow component again;

Described filter is made up of first inductance, two inductance of second inductance and an electric capacity;

First rectifier cell of first rectification circuit exchanges the end serial connection of output in the rectifier with first of a DC-AC inverter, and the other end of an other end of first rectifier cell and the output of DC-AC inverter links to each other with GNDS with node F1 respectively; Second rectifier cell of first rectification circuit exchanges the end serial connection of output with first of second inverter, and the other end of the other end of second rectifier cell and the output of DC-AC inverter links to each other with GNDS with node F1 respectively; First rectifier cell of second rectification circuit at one end is connected in series with the 2nd AC of first inverter output, and the other end of the other end of first rectifier cell and the output of DC-AC inverter links to each other with GNDS with node F2 respectively; Second rectifier cell of second rectification circuit at one end is connected in series with the 2nd DC-AC inverter output of second inverter, and the other end of the other end of second rectifier cell and the output of DC-AC inverter links to each other with GNDS with node F2 respectively;

An end of first inductance and second inductance all links to each other with an end of electric capacity in the filter, and an other end of electric capacity is connected with the ground (GNDS) of this converter; The output of the rectifier of the first full rectification circuit in an other end of first inductance and the rectifier links to each other with the tie point (F1) of continued flow component, and the output of the rectifier of second rectification circuit in an other end of second inductance and the rectifier links to each other with the tie point (F2) of continued flow component.

The PWM of dual-bridge DC-DC converter of the present invention and phase shift mixing control method is characterized in that: described PWM and phase shift mixing control method are:

(1) receives the required duty cycle signals that is produced by Voltage Feedback ring or current feedback ring;

(2) produce:

(a) phase shifting control and pairing 4 gate drive signals (Vgs1, Vgs2, Vgs3 and Vgs4) drive a dual-bridge DC-DC converter the first and second two DC-AC inverters with the output voltage of regulating converter and the purpose that reaches zero voltage switching, this control generally is the adjusting when being used for output voltage and being higher than half maximum output voltage;

(b) PWM control and pairing 4 gate drive signals (Vgs1, Vgs2, Vgs3 and Vgs4) the first and second two DC-AC inverters driving a dual-bridge DC-DC converter to be regulating the output voltage of converter, and this controls generally is adjusting when being used for output voltage and being equal to or less than half maximum output voltage.

Major advantage of the present invention:

(1) in normal output voltage adjustable range, two DC-AC inverters all are operated in 50% constant duty ratio, and circuit is easier to realize ZVS.

(2) improve efficiency of energy delivery to greatest extent from former limit to secondary; The converter of being invented can transmit energy to secondary during D and 1-D.

(3) in loop of power circuit, do not have circulating current, improve power converter efficient.

Description of drawings

Fig. 1: the block diagram of dual-bridge DC-DC converter and controller thereof;

Fig. 2: the voltage oscillogram after the rectification on the outputting inductance;

Fig. 3: two half-bridge DC-DC converter circuit diagrams of band diode rectification output circuit;

Fig. 4 A: the typical voltage and current waveform in traditional Z VS full-bridge direct current-former limit of DC converter power transformer;

Fig. 4 B: the typical voltage and current waveform in the former limit of dual-bridge DC-DC converter power transformer;

Fig. 5: crucial voltage and current waveform;

Fig. 6: the bridge DC-DC converter circuit diagram of enjoying a double blessing of band diode rectification output circuit;

Fig. 7: one is used to produce the circuit diagram of bridge DC-DC converter bridge drive signal of enjoying a double blessing;

Fig. 8: synchronous rectification output circuit figure;

Fig. 9: PWM and phase shift mix the controller block diagram of control;

Figure 10: PWM and phase shift mixture control signal waveforms;

Figure 11 a: circuit diagram that utilizes existing phase-shift controller to produce PWM and phase shift mixing control.

Embodiment

In conjunction with the accompanying drawings, structural feature of the present invention is: described dual-bridge DC-DC converter comprises inverter, rectifier and filter, direct voltage is input to inverter, the interchange output of inverter is input to the ac input end of rectifier again, and the dc output end of rectifier is again by the direct voltage behind the filter output transform;

An end of first inductance and second inductance all links to each other with an end of electric capacity in the filter, and an other end of electric capacity is connected with the secondary ground (GNDS) of this converter; The output of the rectifier of the first full rectification circuit in an other end of first inductance and the rectifier and the tie point (F1) of continued flow component link to each other, and the output of the rectifier of second rectification circuit in an other end of second inductance and the rectifier and the tie point (F2) of continued flow component link to each other.

The DC-AC inverter circuit be semibridge system or full-bridge type; The right power transformer that has two secondary windings of a former limit winding at least of each DC-AC inverter, and can produce symmetry, the square wave of isolation or similarly alternating voltage output.The secondary winding of power transformer is the centre cap formula normally; Two centre caps of the transformer of converter link to each other with the ground (GNDS) of secondary usually simultaneously.This connection diode rectifier circuit.When rectifier cell was switching tube (often being referred to as synchronous rectifier), transformer secondary winding was then received GNDS by synchronous rectifier.Power MOSFET is the synchronous rectifier of using always.Two inputs of each full-wave rectifying circuit are received an end of the secondary of a transformer respectively, and these two full-wave rectifying circuits and two outputting inductances are connected into electric current and increase form doubly, to reduce or to cancel the ripple of output current.When PWM and phase shift mixture control are regulated in the output of soft start or low pressure, output pwm signal; When the duty ratio of PWM reaches 50%, and when the high duty ratio demand was arranged more, controller then forwarded the phase shift pattern to, produces phase-shifted control signal and drives two DC-AC inverters.This controller also can produce corresponding gate drive signal from these phase shift signals and give synchronous rectifier and continued flow switch element.DC-AC inverter with leading phase is called as leading inverter, and the DC-AC inverter of phase lag then is called the hysteresis inverter simultaneously.When converter normally moves, be to be operated in the phase shift pattern.By moving the phase place of this two DC-AC inverter, each rectification circuit has the overlapping and the no-voltage part of different transformer output voltages, thereby the output dc voltage of converter is regulated.At the lap of transformer output voltage, the common output current of two DC-AC inverters.And in the no-voltage part, the continued flow component of rectification circuit passes logical output current, thereby point (continued flow component) beginning from then on, does not promptly have circulating current.

These DC AC inverters can be oscillation mode, and its former limit circuit is an oscillating circuit.They also can be non-oscillation mode.For describing spirit of the present invention best, the doube bridge converter of non-oscillatory type is used as example and describes in detail.There are two kinds of different structures on the former limit of converter, and secondary also has two kinds of different structures.A kind of DC-DC converter can be formed by the combination in any of their former secondary circuits.

The circuit on former limit can be half-bridge DC-AC inverter or full-bridge DC-AC inverter.When normal operation, these DC-AC inverters all operate in about 50% duty ratio.If there is not magnetic bias, when the magnetizing current of their power transformer finishes in per half switch periods, always reach a constant peak value.When all switch opens of the brachium pontis of DC-AC inverter, peak value magnetizing current and the electric current that is coupled to former limit from secondary discharge and recharge the parasitic capacitance of switch, reduce to zero up to the voltage of transformer coil.Then, the hysteresis inverter utilizes magnetic energy, continues its change of current; The leakage field energy that leading inverter then relies on its transformer carries out the change of current.The transformer magnetizing current that suitable meter is established generally can both store enough energy makes brachium pontis realize ZVS.ZVS when leading inverter then needs an additional inductor outside the transformer leakage inductance to come for underloading usually stores enough energy, and this additional inductor often is called the vibration inductance.It helps soft switch (ZVS) but it may produce higher spike and oscillating voltage on the output rectifier cell; Thereby at transformer and the vibration inductance place that links, might need a pair of clamper to power supply+,-clamp diode of the utmost point, in the due to voltage spikes of clamper transformer termination, they also clamper the due to voltage spikes of output rectification circuit, this clamp circuit captures the most transient current that is caused by the reverse recovery of rectifier cell, has reduced the vibration of voltage; The energy that part is caught in is depleted on the loop of power circuit, and remaining part then is used to ZVS and feeds back to DC source, thereby the efficient of circuit is improved.

Not as conventional ZVS full-bridge converter, the voltage change ratio dv/dt of the switch element of hysteresis inverter of the present invention depends on load fully; After power transformer changed its polarity of voltage, the secondary current that is coupled to former limit was zero, and transformer coil becomes open circuit in fact; Do not considering that magnetizing current is only electric current under (transformer) small leakage field energy situation, the parasitic capacitance of switch element is being discharged and recharged and realizing ZVS with voltage change ratio dv/dt very slowly.This circuit characteristic has reduced the EMI when heavily loaded, and serious EMI problem mostly occurs in heavy duty.

The circuit of secondary can be the rectification circuit of diode-type, also can be to use switch element, as MOSFET, circuit of synchronous rectification.The converter of band diode rectifier circuit is usually used in high output voltage and high power circuit.The converter of band circuit of synchronous rectification then more is applicable to the application of low output voltage, as bus converter etc., to improve circuit efficiency.

The various preferential and characteristics selected for use of the present invention have been summarized in above explanation on a large scale, understand following invention details better so that be familiar with the people of this respect technology.These people also should figure out them can realize purpose of the present invention in disclosed notion and side circuit for establishing source or slightly modified ready-madely.They should know also and recognize that such equivalent structure does not break away from spirit of the present invention that they are still within category of the present invention.

In the following description, be easier to understand in order to make to describe, and the relation between simplified electrical circuit diagram and the waveform, element and node will use letter representation, and circuit box increases numeral with some complicated waveforms with other and represents.

Fig. 1 shows the former limit 10 of a DC-DC converter, secondary 20 and PWM and phase shift mixture control 22; Former limit 10 is made up of DC-AC inverter 12 and 14, and secondary is by two full bridge rectifiers 21 and 23, and output filter 25 compositions, and when converter used phase shifting control, the phase place of DC-AC inverter 12 always was ahead of DC-AC inverter 14.Because this phase relation, DC-AC inverter 12 is called as leading inverter, and 14 of DC-AC inverters are called as the hysteresis inverter simultaneously.Because these inverters are bridge architectures, they are also referred to as leading bridge-type inverter and hysteresis bridge-type inverter.Former limit 10 of converter and DC power supply+,-end, promptly Vin+ and Vin-link to each other.Vin-links to each other with former border district (hereinafter to be referred as GNDP) usually.Two DC-AC inverters respectively have a power transformer, and each transformer respectively has two with the centre tapped secondary winding of turn ratio band.Centre cap all links to each other with secondary ground GNDS with negative pole output Vo-, and they also link to each other with the earth usually.The output M1 of these two transformers is connected to rectification circuit 21 with M2 (preferably they have identical polarity).21 of rectification circuits are by rectifier diode Ds1 and Ds3, and sustained diode s5 forms.The negative electrode of diode Ds1, Ds3 and Ds5 is received node F1.The anode of continuous diode Ds5 is received GNDS.The output N1 and the N2 of other two transformers then receive rectification circuit 23, and rectification circuit 23 is made up of rectifier diode Ds2 and Ds4 and sustained diode s6.The negative electrode of Ds2, Ds4 and Ds6 links to each other with node F2, and the anode of sustained diode s6 links to each other with GNDS.The end of two outputting inductance Lo1 and Lo2 links to each other with Vo+, and the other end then links to each other with F2 with F1 respectively.Output capacitance Co is connected between dc output end Vo+ and the Vo-.Lo1, Lo2 and Co form a filter 25.A controller 22 has feedback input and the brachium pontis drive signal Vgs1 of an output voltage V o, Vgs2, the output of Vgs3 and Vgs4 at least; This controller can switch between PWM pattern and phase shift pattern smoothly.

Fig. 2 shows the operation principle of one group of key waveforms and graphic circuit.Waveform VM1 and VN1 are the output voltages (VM1 refers to the voltage of node M 1, and identical expression mode also is used for node F1, F2, M2, N1 and N2) of leading inverter, when normal operation, promptly Vo＞ ¹/ ₂The flat-top voltage of VF1 the time, VM1 and VN1 are a pair of auxilliary mutually waveforms, VM2 and VN2 also are a pair of auxilliary mutually waveforms.Waveform VF1 and VF2 are rectification circuit 21 when the relevant φ of being with the hysteresis inverter of leading inverter and 23 output voltage.Can see that when changing phase angle φ, output voltage V o can be regulated, and each inverter all still operates in 50% duty ratio.As everyone knows, 50% duty ratio is the optimum working mode of an inverter circuit, and this pattern has been widely used for the design of bus voltage converter etc.

Shown in Figure 3 is two half-bridge converters of band diode rectifier circuit.The former limit 110 of converter is that leading half-bridge inverter 112 and hysteresis half-bridge inverter 114 are formed.Leading inverter 112 has a pair of power switch pipe Q1 and Q2.Q1 and Q2 are serially connected with the A point and are attempted by an arm that forms leading inverter between direct-flow input end Vin+ and the Vin-.Dq1 and Dq2 are respectively that the body of power switch Q1 and Q2 is taken diode.Cq1 and Cq2 are the output capacitors of Q1 and Q2, and its value comprises the parasitic capacitance and the external capacitor (if any) of switching tube.Power switch can be MOSFET (a metal oxide silicium field effect transistor), IBGTs (igbt), or other thyristor.All circuit diagrams in this file are all used the symbol of MOSFET.But use the also switching tube of available other form.The end of inductance L r is that node A links to each other with the serial connection point of Q1 and Q2, and the other end then is connected in Node B with the end of power transformer T1.If needed, two clamp diode Dc1 and Dc2 also be serially connected on the Node B and clamper to Vin+ and Vin-, the other end on the former limit of transformer T1 links to each other with the serial connection point C of two half-bridge capacitor C 1 and C2.After C1 and the C2 serial connection, receive between Vin+ and the Vin-.

Hysteresis inverter 114 also has a pair of power switch pipe Q3 and Q4.Q3 and Q4 are in the E point and connect and be serially connected between direct-flow input end Vin+ and the Vin-arm that forms the hysteresis inverter.Dq3 and Dq4 are respectively that the body of power switch pipe Q3 and Q4 is taken diode.Cq3 and Cq4 are the output capacitors of Q3 and Q4, its value comprise the parasitic capacitance of switching tube and external capacitor (if any words) end and the C point on the former limit of power transformer T2 join, the other end links to each other with the E point, two inverters are shared capacitor C 1 and C2 as can be seen, and Fig. 3 only shows than suitable transformer coil connection.Such wiring can make to cancel out each other by the transformer primary current ip1 of C1 and C2 and ip2 and reduce current ripple.Relevant waveform as shown in Figure 5, will remake detailed explanation in the back.Other transformer connection mode is also feasible and also can satisfy above-mentioned groundwork principle, but the capacitance current ripple can be big.

The inferior limit 120 of converter, be as shown in Figure 3 one with the same diode-type rectification circuit and output filter shown in Figure 1.Being connected between the transformer that Fig. 3 has more clearly illustrated above detailed description and the rectification circuit.

The drive signal and the typical transformer original edge voltage current waveform of direct-DC converter that Fig. 4 A illustrates an existing ZVS full-bridge (with reference to [1] correlative detail).This converter passes to secondary to energy from former limit during the D of pulse-width modulation, and during 1-D, the voltage V of inverter power transformer _AESubstantially be zero, do not have energy to be passed to secondary, yet circulating current ip but still cause considerable power consumption by most loop of power circuit.

Shown in Fig. 4 B is drive signal and the typical transformer original edge voltage and the current waveform of a phase shift dual-bridge DC-DC converter.35 of waveform shows the voltage and current oscillogram on the former limit of leading inverter power transformer, 36 voltage and current waveforms that show the former limit of hysteresis inverter power transformer of waveform.Can be clear that two inverters of lead and lag all are to be operated in 50% duty ratio, simultaneously the current i p1 of transformer and ip2 respectively with their voltage Vp1 and Vp2 homophase.In other words, converter can be sent to time limit to energy from former limit during D and 1-D.Because rectifier and outputting inductance Lo1 and Lo2 are connected into electric current to increase a times formula, each inverter is exported the output current of half approximately during D, and exports the electric current of half jointly at a 1-D period two inverter, and second half electric current then flows through continued flow component Ds5 or Ds6.This characteristic that can transmit energy during D and 1-D is circuit of the present invention one of the most attractive part.With can only compare the design of effective duty ratio at the transformer of 80% conventional ZVS full-bridge converter usually, it is littler that the magnetic core of converter of the present invention can be used; Because no circulating current, the RMS electric current of transformer is less, and the while uses dual transformer, this topology to be particularly suitable for high efficiency again, high-power and highly little power supply designs.

The expansion of 3 pairs of half-bridge converters of Fig. 5 displayed map the details of key waveforms.In Fig. 5, Dead Time is exaggerated, so that find out the variation of voltage and current in transient state best.Waveform 40 is voltage waves of Q1 and Q2 grid source electrode (drive signal); Waveform 41 is gate-source voltage waveforms of Q3 and Q4;

Waveform

42 and 43 is lead and lag inverter original edge voltage and current waveform;

Waveform

44 and 45 is the voltage waveforms after the rectification of node F1 and F2; Waveform 46 shows the waveform of outputting inductance and total output current; Waveform 47 is electric current and voltage waveforms of capacitor C 1 and C2; Waveform 48 is current waveforms of sustained diode s5 and Ds6.For the convenience that circuit is described, the reference direction of each voltage and current that Fig. 3 is also given, simultaneously for the ease of understanding the operation of circuit, below selecting with t1 is that the one-period of starting point describes in detail circuit, this one-period is divided into 5 periods simultaneously again;

1, period 1 (t1≤t＜t2); In this period, switching tube Q1 and Q4 are conductings, and t1 is that sustained diode s5 finishes that moment that it oppositely recovers.The reverse recovery current of Ds5 is coupled to the former limit of transformer, major part is stored in inductance L r's (this transient state) energy and is vised by clamp diode Dc1, all the other parts are scattered in the energy in former two limit leakage inductances of transformer T1, then Dc1 can't catch, and this energy can cause some voltage oscillations at node N1; For reducing this vibration, during the design transformer, leakage inductance is as much as possible little.Captive energy circulates in the loop of forming with Q1, L2 and Dc1 with the form (iD1) of electric current, and decays along with the loss of power.Voltage on C1 affacts in the former limit of transformer T1, and the voltage of C2 also acts on the transformer T2.The voltage of C1 and C2 is coupled to the transformer secondary, affacts on the output filter 125 by output rectifying tube Ds1 and Ds4 respectively then.In this period, energy is delivered to secondary from former limit.Inductive current i _L01And i _L02Promptly rise with certain slope, this slope is voltage and the inductance value that depends on inductance two ends.The voltage of capacitor C 1 and C2 is in each the period section of having change, but this change should be inapparent.The amplitude of change depends on switching frequency, the transformer turn ratio, and load current and capacitance, but the mean value of C1 and C2 voltage should all equal half of supply voltage when stable state.

2, period 2 (t2≤t≤t3): switching tube Q ₄Be turned off Q at t2 ₄After the disconnection, be coupled to the inductance L on former limit ₀₂Current i _L02' almost be linearly to Q ₄Capacitor C q4 charge.As the voltage of Cq4, V _E, when being charged to the voltage that is higher than C2, being added to voltage on the transformer T2 and changing its polarity for just.Meanwhile, be added in the secondary voltage of the T2 on the node N2 but by just becoming negative.Thereby inductive current i _L02Just upload and move on on the sustained diode s6 from Ds4.

Leading inverter keeps original state, and continuation powers up by diode Ds1 and is pressed on node F1.The rectifier diode Ds3 and the Ds4 of bridge of lagging behind simultaneously still is in off-state.At this moment in the section, the magnetizing current of transformer T2 continues Cq4 is charged.As long as this magnetizing current can satisfy following the requirement:

I_{m 2} &GreaterEqual; 0.5 \times V_{in} \times \sqrt{(Cq 3 + Cq 4) / Lm 2} - - - (1)

Here V _InBe input direct voltage, L _M2It is the magnetizing inductance of transformer T2.Before T3 was driven conducting, the voltage of Cq4 can be done and fill height and taken diode Dq3 clamper in the input DC source by the body of Q3 at Q3.When Cq4 was charged to DC input voitage, Cq3 was just discharged fully, thereby Q3 is driven conducting when its parasitic capacitance voltage is zero.The output voltage V M2 of transformer T2 reaches the same value of output voltage V M1 of transformer T1 at this moment, and rectifier diode Ds3 begins soft conducting, and the lead and lag inverter also just begins common output current i _L01

At voltage V _EBehind the DC input voitage mid point, because the magnetizing current of transformer is only electric current that Cq4 is charged and Cq3 is discharged, and this electric current in heavy load scope very usually than little many of the load current that is coupled to former limit, so the voltage change ratio on the switching tube is significantly slack-off.These characteristics can greatly reduce EMI, especially carry complete, and complete carrying are that EMI is the most serious the time.

3, the period 3 (t3＜t＜t4): in this period, two common output current i of CD-AC inverter _L01Because output voltage V M1, the VM2 of two transformers are almost equal, electric current is also slow usually from the speed that leading inverter is diverted to the hysteresis inverter, and therefore, leading half-bridge inverter is often got the electric current of Duoing than the hysteresis half-bridge inverter.Meanwhile, sustained diode s6 keeps the state of a period on it, continues conduction current i _L02, and because output voltage V o is added on the Lo2 i by counter _L02Electric current begins to descend.i _L02Reduce and i _L01Increase formed current ripples and cancelled out each other, thereby reduced the ripple of output current.

4, period 4 (t4≤t＜t5): Q ₁Turn-off at the t4 point.The current i of vibration inductance _LrBegin parasitism appearance Cq2 and Cq1 are put charging respectively.This current i _LrBao Shi be coupled to electric current, transformer magnetizing current and the reverse recovery current that is captured by clamp diode Dc1 in the period 1 that the leading inverter on former limit is got.Along with electric current constantly shifts to the hysteresis inverter from leading inverter, i _LrDescend.At i _LrBefore dropping to the magnetizing current of only surplus transformer T1, diode Ds1 keeps conducting.At this moment in the section, as long as the output current of converter reaches certain value, when vibration inductance L r stored enough energy, the electric charge of Cq2 just can be discharged fully, thus realization ZVS.If stored energy is not enough, before parasitic capacitance Cq2 electric charge was discharged fully, Ds1 is soft to be opened, and transformer T1 original edge voltage, Vp1 begin to descend, and finally it changes its polarity.Because in continuous conduction mode (CCM), outputting inductance current i _L02Still flow through Ds6, the inferior limit of transformer T1 is in fact by Ds2 and Ds6 short circuit, and therefore, the magnetizing current of transformer T1 can't further participate in the discharge to Cq2.Yet as long as this magnetizing current can meet the following conditions, vibration inductance L r just can continuation vibrates with Cq1 and Cq2 and thoroughly Cq2 is discharged:

I_{m 1} &GreaterEqual; 0.5 \times V_{in} \times {}^{i}{\sqrt{(Cq 1 + Cq 2) / Lr}} - - - (2)

Here V _InIt is the input voltage of DC converter;

As long as before switch conduction, add suitable Dead Time (t4-t5), be driven conducting at the t5 point when Q2 just can be zero at its parasitic capacitance voltage, thereby realize ZVS.

When it must be noted that zero load the analysis of lead and lag inverter with above-mentioned be different.When zero load, these two bridges all are operated in the free-run mode of LC.Because the natural characteristic of this half-bridge, as long as add suitable Dead Time between the switch of two complementations, ZVS just can relatively easily realize.

5, period 5 (t5≤t＜t6): at Q ₂After the t5 point is driven conducting, inductive current i _LrQuickly fall to zero, and beginning increases oppositely.When it surpasses sustained diode s6 conducting current i at the couple current of secondary _L02During with the reverse recovery current of diode, Ds6 just begins to open at the t6 point; Because the vibration inductance subtracts the rate of change of electric current significantly, reverse recovery current reduces, and relative EMI also reduces.

T6 is the terminal point of first half period, also is the initial point that opens of next half period, but different be the element that participates in next half period action, be the complementary elements of the first half period element.

Clearly, adopt phase shifting control, the adjustable range of output voltage is between the maximum output voltage of its maximum output voltage and 50%.Its maximum output voltage is the flat-top voltage of the equivalent voltage power transformer secondary afterwards of deduction rectifier diode, the loop of power circuit loss of voltage and duty-cycle loss.When 50% maximum output voltage, two half-bridge inverters then are operated in the PWM pattern rather than 50% duty cycle mode continues to regulate its output voltage at soft start or at the bottom of requiring output voltage.

Fig. 6 shows is the former limit of bridging parallel operation of enjoying a double blessing.The former limit 210 of converter is made up of a leading full-bridge inverter 212 and hysteresis inverter 214, and leading inverter 212 has two couples of power switch Q1-Q2 and Qc1-Qc2, and every pair of pipe is serially connected in two pairs of arms that form full-bridge between dc output end Vin+ and the Vin-.Dq1, Dq2, Dqc1 and Dqc2 are respectively that the body of 4 switching tube Q1, Q2, Qc1 and Qc2 is taken diode, and Cq1, Cq2, Cqc1 and Cqc2 are respectively Q1, Q2, Qc1 and Qc2, and its value comprises the parasitic capacitance and the external capacitor of switching tube.One of inductance L r terminates to the serial connection point A of Q1 and Q2, and the other end then power transformer T1 one end links to each other in Node B.If necessary, two clamp diode Dc1 and Dc2 are at B point serial connection and clamper input Vin+ and the Vin-to DC power supply; The other end of transformer is then received the serial connection point C of Qc1 and Qc2.

Hysteresis inverter 214 also has two couples of power switch pipe Q3-Q4 and Qc3-Qc4, and every pair of pipe is serially connected in the body that other two arm: Dq3, Dq4, Dqc3, Dqc4 of formation full-bridge are respectively 4 switching tube Q3, Q4, Qc3 and Qc4 between dc output end Vin+ and the Vin-and takes diode; Cq3, Cq4, Cqc3 and Cqc4 are respectively the electric capacity of Q3, Q4, Qc3 and Qc4, and its value comprises the parasitic capacitance and the external capacitor of switching tube.The end of transformer T2 links to each other with the serial connection point E of Q3 and Q4, and the other end is linked to each other by the serial connection point C ' with Qc3 and Qc4.

Power switch pipe can be MOSFET, IGBT or other thyristor.Respectively by Vgs1, two insulation isolation signals that Vgs2, Vgs3 and Vgs4 produce drive switching tube to Q1/Qc1, Q2/Qc2, Q3/Qc3 and Q4/Qc4.Circuit shown in Figure 7 and signal will be described in detail below.

Shown in Figure 7 is to utilize gate driving transformer Tg1 and Tg2 to produce the gate drive signal of isolate complementary.Can see to the gate drive signal of Q1/Qc1, Q2/Qc2, Q3/Qc3 and Q4/Qc4 respectively with (Vgs1-Vgs2), (Vgs2-Vgs1), (Vgs3-Vgs4), (Vgs4-Vgs3) same polarity.Vgs1 and Vgs2 are the signals to the mutual complementation of leading inverter.Vgs3 and Vgs4 are the signals to the mutual complementation of hysteresis inverter.Other circuit as managing the circuit that driving element is formed by logical circuit and height, also can be finished identical functions.Thereby also should belong to category of the present invention.

The full-bridge inverter of each lead and lag himself may operate at PWM or phase shift pattern, yet because the simplification of PWM control, the control that it is more convenient when being used for the startup of converter and low output voltage.Duty ratio at two inverters reaches after 50%, and they then begin mutual phasing and regulate output voltage.The grid drive signal of having ignored Qc1-Qc4, the control of the bridging parallel operation of enjoying a double blessing and grid drive signal can be used for two half-bridge converters.

Shown in Figure 8 is the secondary 320 of the doube bridge converter of a band circuit of synchronous rectification.Use for low output voltage, the rectification circuit power consumption of diode-type is quite big, and may be directed at heat dissipation problem.In 12V or the more power supply design of low output voltage, circuit of synchronous rectification is used very extensive, and plays the main flow effect.Power MOSFET is the synchronous rectification element, especially the N-channel MOS FET that widely use.The source electrode of N-channel MOS FET normally links to each other with circuit ground, has so just simplified the design of gate driver circuit.Circuit of synchronous rectification 321 and 323 shown in Figure 8 is the rectification circuit differentiation by the diode-type of Fig. 3.Substitute with MOSFET diode, and rearrange after, all MOSFET now all with secondary ground GNDS serve as with reference to.Qs1, Qs2, Qs3 and Qs4 are lock-in tube (being called for short SynFET), and Qs5 and Qs6 have substituted sustained diode s5 and Ds6, and Ds1-Ds6 can be that the body of MOSFET is taken diode, also can be external parallel diode.The source electrode of MOSFET Qs1-Qs6 is all received GNDS.The transformer T1 and the T2 of leading inverter and hysteresis inverter, each all has two independently secondary coils.The drain electrode of SynFET Qs1 and Qs2 links to each other with two secondary coil terminations with opposed polarity of transformer T1 respectively.The drain electrode of Qs3 and Qs4 simultaneously also links to each other with 2 secondary coil terminations with opposed polarity of transformer T2 respectively.Other has the transformer T1 of same reference polarity and receive respectively on node F1 and the F2 termination of T2; The working method of lock-in tube rectification circuit and the rectification circuit of diode-type are just the same.Their logical relation of gate drive signal Vgss1-Vgss6 shown in Figure 10 below will be done to explain in detail.

Fig. 9 is the block diagram of a PWM and phase shift mixture control 122.Controller 122 can be operated in PWM and phase shift pattern, and can be smoothly from a kind of mode switch to another kind of pattern.This controller has at least one Voltage Feedback input, Vfb, and it preferably also has current sense input i _sControlled input Td with Dead Time.Current sensing signal i _sBe the transformer primary current after the rectification | ip1| and | the ip2| sum.Ip1 and ip2 can measure with current sensor or other high-tension current transducer.For two half-bridge converters, best current sensor position should be at transformer with outside electric capacity links to each other.To reduce the common mode voice of current signal.The normally resistance or the electric capacity that link to each other with Td are used for the programming of Dead Time.Current signal i _sCan be used for the circuit overcurrent protection and also can be used for spike formula current loop control.

Controller also should have following components: (1) Voltage Feedback input, and this input generally is the error output signal of Voltage Feedback ring or current feedback ring; Input is set in (2) dead bands, is used for the Dead Time between the configuration switch pipe; (3) phase-shift circuits, it can produce duty cycle control signal (Comp) and 4 drive signals, and these drive signals can move one of them phase place of two DC-AC inverters; (4) saw-toothed wave generator, it can produce first ramp signal and be used for PWM control.(5) crest voltage testing circuits, it can detect or set the crest voltage of sawtooth waveforms; (6) signal superimposers, it can be used for phase shifting control with sawtooth waveforms and second ramp signal of crest voltage stack generation detected or that set of input; (7) PWM generator, it is that a comparator is by relatively first ramp signal and duty cycle signals (Comp) produce PWM; (8) 4 gate drive signals, it be by with 4 drive signals of pwm signal and phase-shift circuit output with produce; (9) one current detection signal input, it is the signal that is formed by stacking after the former limit circuit rectification of the first and second DC-AC inverter transformers; (10) 4 gate driving output signals (Vgss1, Vgss2, Vgss3 and Vgss4), they are used for the driving of synchronous rectifier, its corresponding D of its logical AND C-AC inverter switching device pipe drive signal unanimity, these signals normally use when the phase shift pattern; The gate driving output signal of (11) two continued flow switch element (Vgss5 and Vgss6), these signals also normally use when the phase shift pattern; Vgss1, Vgss3, Vgss5 are used for first rectification circuit, and Vgss2, Vgss4, Vgss6 are used for second rectification circuit,

Figure 10 illustrates the allusion quotation shape output waveform of PWM and phase shift mixture control./ CLOCK is a controller internal clocking waveform.It is the controller heartbeat, and other signal is all as reference.Ramp ﹠amp; Comp shows the relativeness of duty cycle command signal Comp and sawtooth signal Ramp1 and Ramp2.When voltage or average-current mode control, duty cycle command signal Comp is the output of the error amplifier of Voltage loop or average current ring.These signals are linked comparator and are produced required PWM and phase shift drive signal.In order to produce PWM and phase shift signal, Ramp preferably will have two-layer, i.e. Ramp1 and Ramp2, as shown in figure 10.Ground floor (Ramp1) is the sawtooth waveforms with thin grey line drawing, and the second layer (Ramp2) is represented with thick line.When the Comp signal was within ground floor Ramp1, controller produced PWM drive signal Vgs1-Vgs4, did not preferably produce the gate drive signal of SynFET and free wheeling mosfet simultaneously, to avoid the unnecessary transition and the possibility of pipe conducting simultaneously up and down.When the Comp signal enough high, and when entering the Ramp2 layer, pwm signal Vgs1-Vgs4 all reaches their maximum duty cycles of 50%, Vgs3 and Vgs4 begin to move their phase place, controller is exported the gate drive signal Vgss1-Vgss6 of SynFET and free wheeling mosfet simultaneously, to reduce the power consumption of rectification circuit.Drive signal Vgss1, Vgss2, Vgss3 and Vgss4 respectively with Vgs1, Vgs2, Vgs3 and Vgs4 homophase.Vgss5=/(Vgss1+Vgss3) in logic, Vgss6=/(Vgss2+Vgss4).

The waveform that Figure 10 gave is no dead band, and when the design of side circuit or IC core electricity, these Dead Times are very crucial, and should adjust to and both avoid managing up and down straight-through, is again to be enough in soft switch just.

Figure 11 shows that a usefulness has the phase shifting control chip now, as UCC3895, circuit realize that PWM and phase shift mix control and produce the gate drive signal of main switch as shown in figure 10.This control circuit 400 has the phase-shift controller 401 of a routine, one by the bipolar brilliant pipe Q10 of NPN and a voltage divider of being made up of divider resistance R1 and R2, a pull-up resistor R5,4 pull-down diode D1, D2, D3 and D4, a due to voltage spikes detector 402.Signal Ramp1 is the voltage that comes from time oscillating capacitance (CT).The output of voltage divider is Ramp1.The crest voltage of peak voltage detector 402 detection signal Ramp1, and this voltage Vpeak remained on its output.Vpeak voltage is by selecting different R1 and R4 ratio to change, and determines that due COMP voltage of signals level switches PWM and phase shifting control pattern; When this duty cycle command signal of Comp was lower than Vpeak, this control circuit 400 just operated in the PWM pattern.This PWM output is an open-collector circuit, and this signal is repaiied output OutA, the OutB, OutC and the OutD that cut phase-shift controller and produced desired gate drive signal Vgs1, Vgs2, Vgs3 and Vgs4.R6, R7, R8 and R9 are used for limiting when output that controller 401 output is compared device VCMP2 undercuts its electric current.When the voltage of signal Comp was higher than Vpeak, the output of VCMP2 was always drawn high by R5, and D1, D2, D3 and D4 keep apart controller 401 outputs with the output of comparator VCMP2 simultaneously; The comparator VCMP1 of controller 401 compares its input signal Ramp2 and Comp produces phase shift signal; Therefore circuit 400 just can switch to the phase shift pattern smoothly.Otherwise, this controller also can be smoothly from the phase shift mode switch to the PWM pattern.Duty cycle command signal Comp is the output of error amplifier EA.The error signal of Voltage loop is preferably received in its "+" input, and its "-" input is simultaneously received current detection signal is and received Comp by R3 by R4.Current detection signal is is transformer primary current ip1 and ip2 (as shown in Figure 9) sum after the rectification.The voltage of signal Comp can be represented with following formula.

Voltage=Vfd of Comp * (R3+R4)/R4-is * Rs * R3/R4 .... (3)

By selecting different R3 and R4 value, this control voltage can be operated in voltage mode or voltage and current mixed mode as can be seen.When R4 opened a way, the voltage of Comp equaled Vfb, this means it is voltage mode.When R4 reduces or Rs when increasing, current i s has more influence to control, and the operation of circuit more approaches current-mode.

The invention be used for the new method that the PWM of power converter and phase shift mix control.Fig. 9 and Figure 10 have illustrated this control principle concisely.Figure 11 has provided a practical circuit understand better so that know the people of this technology, but this and do not mean that this is that a limited method realizes this control.Any circuit with this unique control all should belong to category of the present invention.

From the understanding to the invention circuit operation of above-mentioned institute, can see circuit structure of the present invention and modulator approach, with having very in the past Big difference. These circuit and their control method have the advantage of nearly all half-bridge and full-bridge converter. These advantages Can be summarized as follows:

1, the lead and lag inverter all is operated in constant 50% dutycycle, and circuit is easier to realize ZVS.

2, improve to greatest extent efficiency of energy delivery from former limit to inferior limit; The converter of inventing can be in D and 1-D phase Between transmit energy, the power transformer original edge voltage is a square-wave voltage that Dead Time is very little, and with by its electric current homophase.

3, more effectively utilize magnetic element; The power transformer of two DC-AC inverters all is operated in 50% dutycycle, During Design of Transformer, the voltage-regulation in the time of needn't be for load transient is stayed the close design margin of magnetic.

4, in loop of power circuit, do not have circulating current, improve power conversion efficiency.

5, the voltage change ratio of the switching tube of hysteresis bridge is little; The institute of tradition phase shift and PWM control full-bridge or asymmetrical half-bridge The voltage change ratio that switch is arranged all is to become with load. Yet the switch of the hysteresis bridge of the circuit of inventing is at the variation in voltage of half In the scope, the little voltage change ratio irrelevant with load arranged, this feature has alleviated the EMI problem.

6, reduce the reverse recovery current of output rectifier; The vibration inductance not only provides enough energy to be used for soft switch, simultaneously The current changing rate that also reduces rectifier cell can reach more, and hag turn-offs.

7. reduce to greatest extent the vibration of secondary voltage; Phase place diode Dc1 and Dc2 can catch anti-by what be reduced The energy that produces to restoring current. If the leakage field of power transformer can obtain restriction well, good circuit is arranged again simultaneously The plate design, the vibration of secondary voltage just can be hanged down and be need not other absorbing circuit.

8, reduce copper loss; Because the voltage of two power transformers all has the square-wave voltage of very little Dead Time, its electric current of while With corresponding voltage homophase, for same power output, transformer required for the present invention has littler RMS electric current again.

9, utilize current multiplier to reduce the ripple of output current.

10, utilize two power transformer primary currents mutually to cancel reducing current ripple and electric current RMS by half-bridge electric capacity Value; This current ripple is littler than any traditional half-bridge converter.

11, be easier to produce the gate drive signal of lock-in tube SynFET and continued flow tube MOSFET; 4 lock-in tube grids drive Signal is the same with the logic of 4 bridge switch elements, and continued flow tube MOSFET drives the driving signal logic relation letter of signal and lock-in tube Single, need not complicated signal and process.

Claims

1. dual-bridge DC-DC converter, it is characterized in that: described dual-bridge DC-DC converter comprises inverter, rectifier and filter, direct voltage is input to inverter, the interchange output of inverter is input to the ac input end of rectifier again, and the dc output end of rectifier is again by the direct voltage behind the filter output transform;

Described inverter is made up of the first and second two AC-DC (hereinafter to be referred as DC-AC) inverters, and each DC-AC inverter has two first and second ac output end mouths of isolating mutually again;

Described rectifier is made up of the first and second two full-wave rectifying circuits, and each full-wave rectifying circuit is made up of rectifier cell and continued flow component again;

First rectifier cell of first rectification circuit exchanges the end serial connection of output in the rectifier with first of a DC-AC inverter, and the other end of an other end of first rectifier cell and the output of DC-AC inverter links to each other with secondary ground (hereinafter to be referred as GNDS) with node F1 respectively; Second rectifier cell of first rectification circuit exchanges the end serial connection of output with first of second inverter, and the other end of the other end of second rectifier cell and the output of DC-AC inverter links to each other with GNDS with node F1 respectively; First rectifier cell of second rectification circuit at one end is connected in series with the 2nd AC of first inverter output, and the other end of the other end of first rectifier cell and the output of DC-AC inverter links to each other with GNDS with node F2 respectively; Second rectifier cell of second rectification circuit at one end is connected in series with the 2nd DC-AC inverter output of second inverter, and the other end of the other end of second rectifier cell and the output of DC-AC inverter links to each other with GNDS with node F2 respectively;

An end of first inductance and second inductance all links to each other with an end of electric capacity in the filter, and an other end of electric capacity is connected with GNDS; The output of the first full rectification circuit in an other end of first inductance and the rectifier and the tie point (F1) of continued flow component link to each other, and the output of second rectification circuit in an other end of second inductance and the rectifier and the tie point (F2) of continued flow component link to each other.

2. according to claims 1 described dual-bridge DC-DC converter, it is characterized in that: described rectifier and continued flow component are diodes; When output dc voltage after the conversion was positive voltage, the negative pole of all diodes (the K utmost point) should be towards node F1 or F2, and when output dc voltage after the conversion was negative voltage, the positive pole of all diodes (the A utmost point) should be towards node F1 or F2.

3. according to claims 1 described dual-bridge DC-DC converter, it is characterized in that: described rectifier and continued flow component are switching tubes, and when output dc voltage after the conversion was positive voltage, the drain electrode of all switching tubes or collector electrode should be towards F1 or F2; When output dc voltage after the conversion was negative voltage, the source electrode of all switching tubes was then towards F1 or F2.

4. according to claims 1 or 3 described dual-bridge DC-DC converters, it is characterized in that: its switch element can be MOSFET, IGBT or other semiconductor element.

5. according to claims 1 described dual-bridge DC-DC converter, it is characterized in that: the first and second DC-AC inverters in the described inverter are made up of half-bridge inverter, and described each DC-AC inverter comprises:

(a) be serially connected in first and second switch elements of direct current (hereinafter to be referred as DC) input,

(b) be serially connected in first and second electric capacity of DC input,

(c) transformer with at least one primary coil and two secondary coils, primary coil has first end and second end; First end of primary coil links to each other with the serial connection point of electric capacity with switch element serial connection point respectively with second end.

6. according to claims 1 or 5 described dual-bridge DC-DC converters, it is characterized in that:

(a) there is an inductance to be serially connected in first termination of the transformer primary coil of the serial connection point of switch element of first half-bridge inverter and first half-bridge inverter;

(b) first clamp diode and second clamp diode are serially connected in first end of the first half-bridge inverter primary coil, and clamper is at two DC inputs

7. according to claims 1 described dual-bridge DC-DC converter, it is characterized in that: the first and second DC-AC inverters in the described inverter are made up of full-bridge inverter, and each DC-AC inverter comprises:

(a) first and second switch elements that are serially connected in the DC input;

(b) third and fourth switch element that is serially connected in the DC input;

(c) transformer with at least one primary coil and two secondary coils, primary coil have first end and second end to receive two serial connection points of serial connection switch element respectively.

8. according to claims 1 or 7 described doube bridge dc dc converters, it is characterized in that:

(a) inductance is serially connected between first end of the serial connection point of first and second switch elements of first full-bridge inverter and transformer primary coil, to increase the ZVS scope;

(b) first clamp diode and second clamp diode are serially connected in first end of the first full-bridge inverter primary coil, and clamper is between two DC outputs.

9. pulse-width modulation of a dual-bridge DC-DC converter (hereinafter to be referred as PWM) and phase shift mixing control method, it is characterized in that: described PWM and phase shift mixing control method are:

(2) produce:

(a) phase shifting control and pairing 4 gate drive signals (Vgs1, Vgs2, Vgs3 and Vgs4) drive a dual-bridge DC-DC converter the first and second two DC-AC inverters with the output voltage of regulating converter and the purpose that reaches zero voltage switching (hereinafter to be referred as ZVS), this control generally is the adjusting when being used for output voltage and being higher than half maximum output voltage;

10. according to the PWM and the phase shift mixing control method of claims 9 described a kind of dual-bridge DC-DC converters, it is characterized in that: described dual-bridge DC-DC converter is driven by the gate drive signal of 4 isolation, this drive signal is in the PWM mode or change the mode of the first half-bridge DC-AC inverter and the second half-bridge DC-AC inverter phase difference of this converter, makes the output voltage of dual-bridge DC-DC converter adjusted.

11. PWM and phase shift mixing control method according to claims 9 described dual-bridge DC-DC converters, it is characterized in that: it is to be driven by 4 pairs of drive signals of isolating mutually, per 2 pairs drive a full-bridge inverter, every pair of switching tube that drives two diagonal angles, these drive signals are in the PWM mode or change the mode that differs of the first full-bridge DC-AC inverter and the second full-bridge DC-AC inverter of this converter, make that the output voltage of dual-bridge DC-DC converter is adjusted.

12. PWM and phase shift mixing control method according to claims 9 described dual-bridge DC-DC converters is characterized in that: when phase shifting control, have at least the phase place of a DC-AC inverter to be moved the output dc voltage of regulating converter.

13. PWM and phase shift mixing control method according to claims 9 described a kind of dual-bridge DC-DC converters is characterized in that: all DC-AC inverter switch elements operate in the state near 50% duty formula when phase shifting control.

14. according to the PWM and the phase shift mixing control method of claims 9 described doube bridge dc dc converters, it is characterized in that: its correspondent control circuits comprises:

(1) Voltage Feedback input, this input generally is the error output signal of Voltage Feedback ring or current feedback ring;

Input is set in (2) dead bands, is used for the Dead Time between the configuration switch pipe;

(3) phase-shift circuits, it can produce duty cycle control signal (Comp) and 4 drive signals, and these drive signals can move one of them phase place of two DC-AC inverters;

(4) saw-toothed wave generator, it can produce one first ramp signal and be used for PWM control.

(5) crest voltage testing circuits, it can detect or set the crest voltage of sawtooth waveforms;

(6) signal superimposers, it can be used for phase shifting control with sawtooth waveforms and one second ramp signal of crest voltage stack generation detected or that set of input;

(7) PWM generator, it is that a comparator is by relatively first ramp signal and duty cycle signals (Comp) produce PWM;

(8) 4 DC-AC inverter gates drive signal Vgs1, Vgs2, Vgs3 and Vgs4, they be by with 4 drive signals of pwm signal and phase-shift circuit output with produce;

(9) one current detection signal input, it is the signal that is formed by stacking after the former limit circuit rectification of the first and second DC-AC inverter transformers.

15. PWM and phase shift mixing control method according to claims 9 or 14 described dual-bridge DC-DC converters is characterized in that:

(1) 4 synchronous rectifier gate driving output signal (Vgss1, Vgss2, Vgss3 and Vgss4), its logic is distinguished its corresponding DC-AC inverter switching device pipe drive signal Vgs1, Vgs2, Vgs3 are consistent with Vgs4, and these signals normally use when the phase shift pattern;

The gate driving output signal of (2) two continued flow switch element (Vgss5 and Vgss6); Vss1, Vgss3, Vgss5 are used for first rectification circuit, and Vgss2, Vgss4, Vgss6 are used for second rectification circuit, and the logical relation of the gate driving output signal of synchronous rectifier and continued flow switch element is:

Vgss5＝/(Vgss1+Vgss3)

Vgss6＝/(Vgss2+Vgss4)

These two drive signals are used when the phase shifting control pattern usually.

16. PWM and phase shift mixing control method according to claims 9 described dual-bridge DC-DC converters is characterized in that:

(1) phase-shift controller, it has:

(a) operational amplifier+input (EAP);

(b) operational amplifier-input (EAN);

(c) output of an operational amplifier (Comp);

(d) an oblique wave input (Ramp2) is used for phase shifting control;

(e) a ramp signal control end (CT), it connects with an electric capacity usually, changes switching frequency with the change capacitance;

The input of (2) current detecting, this current signal become voltage signal after by an earth resistance;

(3) Voltage Feedback inputs, it links to each other with EAP;

(4) voltage follow triodes, its base stage is connected with CT, and its collector electrode links to each other with the direct current biasing power supply;

(5) voltage dividers, it is to be in series by two resistance, the emitter of a termination triode of resistance string, termination signal ground GND in addition, the serial connection point of two resistance is the output of a ramp signal (Ramp1);

(6) peak voltage detectors, its input is signal Ramp1, is output as the crest voltage of Ramp1;

(7) voltage superimposers, it is superimposed and produce another ramp signal Ramp2 with the crest voltage of Ramp1 and Ramp1;

(8) comparators, it is compared signal Comp and produces a pwm signal with Ramp1;

(9) logical AND circuit, it with each drive signal of this pwm signal and phase-shift controller output by a diode with produce required DC-AC inverter switching device pipe drive signal;

The negative input EAP of the output Comp of (10) resistance concatenation operation amplifiers and operational amplifier is used for voltage mode control;

(11) resistance connect the current detecting input and the negative EAN of input of operational amplifier is used to add current control mode.